Netflix is keeping the heat on U.S. broadband providers to boost bandwidth for its popular video-streaming service, pointing to data it says shows American service providers' connection speeds lag behind those of ISPs in most other countries.

For July, according to the No. 1 subscription-video service, U.S. providers delivered lower average speeds than ISPs in many countries in Europe and the rest of the Americas during primetime hours. The United States ranked 13th on the Netflix ISP Speed Index for the month, with an average user speed of 2.23 megabits per second, among the 20 countries the company tracks.

Why this matters: the higher the bandwidth connection, the better the picture quality and the less chance of buffering interruptions in a video stream. Netflix, which first started ranking ISPs by average connection speed in early 2011, publishes the figures monthly as part of its effort to highlight which providers deliver the fastest average speeds -- and which are the slowest.

Netflix has locked horns with some big U.S. ISPs over the issue of paying for delivering video traffic to their mutual customers. The company has reached deals with Comcast, AT&T and Verizon, under which it is paying those providers for interconnections into their data networks -- but Netflix has argued that such fees are tantamount to an arbitrary toll that it shouldn't have to pay. The FCC in June said it is investigating the issue of interconnection agreements.

According to Netflix, for July, the Netherlands leads in performance, with an average of 3.61 Mbps in July, while Norway, Denmark and Sweden all had speeds of greater than 3 Mbps and the U.K. clocked in at around 3 Mbps. Average speeds in Canada, Finland, Uruguay, Colombia, Brazil, Ireland and Chile each beat out the U.S. last month.

At the bottom of the list was Costa Rica, with an average speed of 1.48 Mbps last month, though "it has steadily improved its performance since we began tracking this year," spokeswoman Anne Marie Squeo said in a blog post.

The speeds Netflix measures reflect the average performance during primetime of all streams on each ISP's network, and are below peak levels performance due to several factors including the variety of video-encoding rates Netflix uses and the variety of devices members use as well as home-network conditions, according to the company.